Field of the Invention
This invention relates to a control apparatus for an autonomously navigating utility vehicle that autonomously navigates and performs lawn mowing and/or other work in a working area delineated by a boundary wire.
Description of Related Art
Among conventional control apparatuses for such an autonomously navigating utility vehicle are known ones that make the utility vehicle travel along the boundary wire while using magnetic sensors to detect magnetic field strength (intensity) generated by electric current passing through the boundary wire and detect moving direction displacement and travel distance of the utility vehicle at this time using an angular velocity sensor and a wheel speed sensor, respectively, so as to generate on a bitmap a travel route representing a boundary (boundary line) of an area to be traveled (working area) (see Japanese Laid-Open Patent Application No. 2012-79022 (JP 2012-79022A), for example).
After generating the travel route representing the boundary of the area to be traveled, the control apparatus of the reference identifies or determines the position of the utility vehicle on the bitmap based on values detected by the angular velocity sensor and the wheel speed sensor. The control apparatus described in the reference is also equipped with a geomagnetic field sensor and calibrates the output of the angular velocity sensor based on the output of the geomagnetic field sensor during straight travel work in a predetermined direction.
However, the control apparatus of the reference may not be able to identify or detect the position (self-position) of the utility vehicle accurately because it identifies the position of the utility vehicle based on values detected by the angular velocity sensor and wheel speed sensor. Moreover, the control apparatus of the reference ensures positional accuracy during straight travel of the utility vehicle by using the output of the geomagnetic field sensor to calibrate the output of the angular velocity sensor. Disadvantageously, a geomagnetic field sensor or other such position detecting sensor is generally costly, so that a configuration equipped with a geomagnetic field sensor increases the cost of the control apparatus as a whole.